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You didn't read the article carefully. One of the things it mentions is that it is 20% less energy dense than lithium ion. Sounds terrible, but the upside is y

You didn't read the article carefully. One of the things it mentions is that it is 20% less energy dense than lithium ion. Sounds terrible, but the upside is you make the car chassis out of battery, so you haven't added weight to it. The net result could be very good, or maybe they need to work on it and improve on the 20%. Going further with the battery news cynicism idea, batteries have steadily improved over the last 50 years, to an amazing degrees, because of steady breakthroughs causing small improvements. It is why we can have iphones and tesla today.

tromp 6y ago
5x less dense is 80% less dense.
- nybble41 6y ago
  "5x less" would be "x - 5x" or -4x, which of course is nonsense as density can't be negative. "5x as sparse" works if you define sparsity as the inverse of density.
  - Dylan16807 6y ago
    Don't be so weirdly picky. "times less" is division.
    - nybble41 6y ago
      Which inconsistency do you prefer? • "90% less than x" does not equal "10% of x" • "90%" does not equal "0.9 times" • "0.9 times less" means multiplication and subtraction (x - 0.9x) but "1.1 times less" means division (x / 1.1) This is one of those cases where we know from the context what was meant but that isn't the same as what was said. Normalizing this abuse of language introduces unnecessary special cases and discontinuities for readers/listeners to deal with and creates ambiguity in situations where one of the two interpretations is not so obviously wrong as it is here. It's better to keep the rules simple: ratios, percentages and "times" always involve multiplication by the original value, and "more" and "less" refer to addition and subtraction. There should be a deterministic 1:1 correspondence between the phrasing and the formula.
      - Dylan16807 6y ago
        Does anyone actually say "zero point ___ times less"? I would say not to do that, and only use "times less" with numbers above 1. That's much easier than dealing with people who calculate percentages wrong or say ambiguous things about large increases.
        nybble41 6y ago
        No, for ratios less than unity most people would use a shorter, more convenient fraction ("nine-tenths") or percentage ("ninety percent") which has exactly the same meaning as the decimal ratio ("zero point nine times"). For fractions the word "times" may be implied rather than explicit; for percentages it's always implied, whereas for decimal ratios it's necessary to distinguish ratios from absolute quantities. These forms are nonetheless all equivalent and substituting one for another should not change the meaning of the phrase. "X more than Y" means addition, even if X is expressed as a ratio ("three times more than Y" equals "300% more than Y" equals "Y plus 300% of Y" equals "Y plus three times Y"). Analogously, "X less than Y" means subtraction, not division, whether X is an absolute quantity, a percentage either less than or greater than 100%, a fraction, or a decimal ratio. This is human language, of course, so you can be as over-complicated, inconsistent, and ambiguous as you want and generally count on sufficiently smart listeners/readers to decode the resulting mess into something intelligible based on context. It's not good style, and it encourages innumeracy and presents math as being more complicated than it should be, but it will usually get the job done.
nybble41 6y ago
> 20% less energy dense than lithium ion That's 20% as dense (1/5 the density), not 20% less dense (4/5 the density). As for replacing the chassis—a Tesla Model S has 1,200 lbs of batteries, and the aluminum chassis weighs 410 lbs. Assuming this new material replaces the aluminum pound-for-pound, that would store enough energy to displace about 82 lbs of ordinary lithium ion batteries for a ~5% reduction in total weight. If the energy density were somehow on par with lithium ion then it would save 410 lbs, or 25% of the total weight.

tromp 6y ago

5x less dense is 80% less dense.

nybble41 6y ago
"5x less" would be "x - 5x" or -4x, which of course is nonsense as density can't be negative. "5x as sparse" works if you define sparsity as the inverse of density.
- Dylan16807 6y ago
  Don't be so weirdly picky. "times less" is division.
  - nybble41 6y ago
    Which inconsistency do you prefer? • "90% less than x" does not equal "10% of x" • "90%" does not equal "0.9 times" • "0.9 times less" means multiplication and subtraction (x - 0.9x) but "1.1 times less" means division (x / 1.1) This is one of those cases where we know from the context what was meant but that isn't the same as what was said. Normalizing this abuse of language introduces unnecessary special cases and discontinuities for readers/listeners to deal with and creates ambiguity in situations where one of the two interpretations is not so obviously wrong as it is here. It's better to keep the rules simple: ratios, percentages and "times" always involve multiplication by the original value, and "more" and "less" refer to addition and subtraction. There should be a deterministic 1:1 correspondence between the phrasing and the formula.
    - Dylan16807 6y ago
      Does anyone actually say "zero point ___ times less"? I would say not to do that, and only use "times less" with numbers above 1. That's much easier than dealing with people who calculate percentages wrong or say ambiguous things about large increases.
      - nybble41 6y ago
        No, for ratios less than unity most people would use a shorter, more convenient fraction ("nine-tenths") or percentage ("ninety percent") which has exactly the same meaning as the decimal ratio ("zero point nine times"). For fractions the word "times" may be implied rather than explicit; for percentages it's always implied, whereas for decimal ratios it's necessary to distinguish ratios from absolute quantities. These forms are nonetheless all equivalent and substituting one for another should not change the meaning of the phrase. "X more than Y" means addition, even if X is expressed as a ratio ("three times more than Y" equals "300% more than Y" equals "Y plus 300% of Y" equals "Y plus three times Y"). Analogously, "X less than Y" means subtraction, not division, whether X is an absolute quantity, a percentage either less than or greater than 100%, a fraction, or a decimal ratio. This is human language, of course, so you can be as over-complicated, inconsistent, and ambiguous as you want and generally count on sufficiently smart listeners/readers to decode the resulting mess into something intelligible based on context. It's not good style, and it encourages innumeracy and presents math as being more complicated than it should be, but it will usually get the job done.

nybble41 6y ago

> 20% less energy dense than lithium ion That's 20% as dense (1/5 the density), not 20% less dense (4/5 the density). As for replacing the chassis—a Tesla Model S has 1,200 lbs of batteries, and the aluminum chassis weighs 410 lbs. Assuming this new material replaces the aluminum pound-for-pound, that would store enough energy to displace about 82 lbs of ordinary lithium ion batteries for a ~5% reduction in total weight. If the energy density were somehow on par with lithium ion then it would save 410 lbs, or 25% of the total weight.